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UNTTnn STATES PATENT Gr mes,

PIERRE MANHES, OF LYONS, FRANCE.

PROCESS OF EXTRACTING GOLD AND SlLVER FROM ORES AND MATTES.

SPECIFICATION forming part of Letters Patent No. 337,967, dated March 16, 1886.

Application filed August 21. 1884. Serial No. 141,151. (No specimens) Patented in France May 10, 1884, No. 162,001 in England July 19, 1884, No. 10,352; in Belgium July 19, 1884, No. 65,821,- in Germany July 21, 1884, No. 30,419; in Austria-Hungary July 24, 1884, No. 18,823 and No. 46,696, and in Spain July 26, 1884, No. 4,355.

To all whom it may concern:

Be it known that I, PIERRE hIANHES, of Lyons, in the Republic of France, have invented an Improvement in Processes of Ex tracting Gold and Silver from Ores and Mattcs, of which the following is a specification.

The object of the process about to be described is the easy and economical extraction of gold and silver contained in mattes, ores, and various auriferous and argentiferous products. The process has been studied specially in view of the extraction of gold and silver contained in copper matte, but it can be applied with equal advantage to ores and various products containing gold and silver, and particularly to complex sulphureted ores. My invention, therefore, is not limited in this particular. Besides economy, facility, and rapidity of execution, it presents over all the processes in use the advantage of not changing the nature of the materials from which the precious metals are extracted, which materials when once deprived of these metals preserve all their properties and qualities copper matte, for instance, when deprived of the gold and silver which it contained, remains in the state of matte, (sulphuret of iron and copper,) so that nothing is changed in its subsequent treatment for copper.

To enable the details of this process to be understood, I will take for example of treat ment that of an auriferous and argentiferous cupreous matte, and the following is how I proceed: The crushed matte, without any preliminary roasting, is mixed as intimately as possible with powdered sal-ammoniac, (chloride of ammonium.) The quantity of this salt employed is very small, in general from one to three per cent. of the weight of the matte; but it is to be understood that this quantity necessarily varies, according to the proportion of the precious metals contained in the matte. The mixture thus prepared is simply heated at a low temperature until the ammoniacal vapors, which are evolved abundantly, disappear. I say heated, and not roasted, because the temperature ought to be very low, as in a simple heating. It ought always to remain below red heat. The matte ought to remain blackthat is to say, it is necessary that the temperature be only sufficient for the decompositionof the sal-ainmoniac without it being sufficiently high to decompose the sulphurets of iron and copper, which ought to remain intact, or almost so.

The heating can be done in a furnace of any kind and on'any kind of a hearth; butiu practiee I preferably use a closed muffle in order to collect the ammoniacal vapors, which are then employed for the reproduction of the salammoniac by the usual processes. When the ammoniaeal vapors have disappeared, which requires but little time, the appearance of the matte has not sensibly changed. Nevertheless the gold and silver are in the state of chlorides, while the iron and copper arein the condition of sulphurets. It only remains to dis solve by one of the known means the chlorides of gold and silver, and the matte, deprived of the precious metals which it contained, is afterward treated in the ordinary manner for copper.

I said that the chlorides of gold and silver formed are dissolved by one of the known means; but by preference I employ for this dissolution the following operations, which are those that have given the best results: First, solution of the chlorides in hyposulphite of soda; second, precipitation of the metals to the state of sulphides by an addition of sulphide of sodium, which reproduces at thesaine time the hyposulphite liquor.

It is useless to describe here these two operations, which are Well known and practiced in many works; besides they do not separately constitute my invention, and I do not claim the ownership of them, reserving to myself, on the contrary, to make the solution of the chlorides by any means which experience shall make known to me as preferable.

My process therefore consists, essentially, of a new mode of forming chlorides of precious metals, and it is characterized by the employment of sal-ammoniac (chloride of ammonium) as the agent for converting the metals into chlorides in conjunction with a heating at a low temperature that does not decompose the sulphurets and other components with which the gold and silver are combined. It differs completely from the processes heretofore employed, not only by that mentioned, but, further, by the suppression of roasting, which renders it more rapid and economical.

I do not claim the use of sal-ammoniac in the extraction of gold and silver from their ores, as this has been used; and I am also aware that sulphide ores'bearing precious metal have, after a preliminary roasting, been chloridized by roasting with salt or sal-ammoniac.

In my improvement the copper matte is not roasted, neither is it altered by the chloridizing operation, except so far as the removal of the precious metals leaves the copper purer.

I claim as my invention A The process herein specified of extracting gold and silver from auriferous and argentif- August, 1884.

PIERRE MANHES.

lVitnesses:

J. P. A. lVIARTIN, J ULEs LEPINETTI. 

